1. Field of the Invention
Embodiments of the present invention generally relate to back-up power systems, and, in particular, to a system for providing back-up battery operated power to an appliance in the event of a power failure.
2. Description of the Related Art
Power outages during times of floods, high wind, wildfires, ice and snow storms, and other natural disasters are relatively common even in the U.S. When power fails, one of the most disturbing consequences is being left in the dark, especially for the elderly or families with small children. To overcome this problem, multiple systems have been developed in the general area of uninterruptible power sources, emergency lighting, and home safety. However, there is still a need to have practical, reliable, cost effective back-up power in the event of an emergency.
Emergency lighting systems for commercial buildings have been continuously improved for many decades and fall into several broad categories of approach to the problem. Systems making use of low voltage alternative light sources, such as, for example, a light emitting diode (LED) that can be battery powered and separately controlled when main lighting fails have been in use in commercial establishments. Another system uses the main lights and a battery backup power system connected in parallel with the main power source. When power fails, a circuit senses the loss of power and switches to the backup unit. However, such systems are designed primarily for commercial application, either directly built into the lighting fixture, a light bulb, or into the control switch and automatically sense loss of power so that there is always some light to evacuate the building. They are complicated, expensive and may require rewiring the building. These are not well suited for the home.
Systems designed for home use include battery back-up night light systems that may be built into the wall switch or into a plug-in night light and become active when a power failure occurs. However, light output is very low corresponding to a night light or a single candle. Manually rechargeable flashlights that do not require batteries are another solution to the problem. In this case there is considerable physical exertion just to maintain enough light to see. This is fine for emergency evacuation but not for waiting in a kitchen or family room until power returns. Another approach is to build a backup battery system into the lamp itself or into the bulb. These devices may require a second switch in addition to the lamp switch to allow turning off the lamp without disabling the emergency lighting feature. Yet another approach is to build a decorative luminary. The problem with these systems is twofold. First, the consumer does not have the freedom to choose the lamp to match interior decor, and even if the backup unit is built into the bulb, the system typically is bulky, the consumer cannot choose the type or light output of the bulb, or a shade may not fit on many lamp systems. Further, due to mechanical size constraints, there is a limited battery size and therefore, a limited length of backup time, typically less than an hour.
There have been significant developments in fluorescent light bulbs to replace traditional incandescent light bulbs for ordinary table and household lamps. The fluorescent bulbs typically are designed for a seven year life, typically provide a variety of light outputs, and have internal phosphors that are warm in color emulating the traditional incandescent lamp. Fluorescent bulbs use approximately 20% of the power commonly used by comparable incandescent lamps. In addition, fluorescent bulbs may be considered “green” or environmentally friendly since they reduce the overall emission of greenhouse gasses, making such bulbs popular in consumer household lighting.
Attempts to put a standard fluorescent bulb into an adaptor for a table lamp and then use a battery backup circuit as a ballast to supply the high voltage and low current needed to operate the fluorescent light also have been developed. The advantage of the fluorescent light is that the power required for a given lumen output is very low and therefore the light will stay on for a relatively long time. However, drawbacks include large, bulky bulbs that may not fit many household appliances, as well as harsh fluorescent light. Finally, there are standby emergency generators that can be directly wired into the main power of a dwelling or building, but these are expensive. Additionally, because the generator power is provided to the entire home without selectivity as to what appliance is powered, the length of time for back-up is generally only two to three days with a single charge of fuel.
Thus, there exists a need for an inexpensive and easily portable back-up power system that is always ready in case of power failure, stays on automatically, may be used selectively for different lighting sources, and provides multiple output levels of power.